From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5240ECAAD4 for ; Tue, 30 Aug 2022 10:24:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 20B86940007; Tue, 30 Aug 2022 06:24:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1BA606B0074; Tue, 30 Aug 2022 06:24:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0D1A9940007; Tue, 30 Aug 2022 06:24:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 019DA6B0073 for ; Tue, 30 Aug 2022 06:24:33 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id C612616105A for ; Tue, 30 Aug 2022 10:24:33 +0000 (UTC) X-FDA: 79855874826.01.78F6616 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf30.hostedemail.com (Postfix) with ESMTP id 2F13E80012 for ; Tue, 30 Aug 2022 10:24:32 +0000 (UTC) Date: Tue, 30 Aug 2022 12:24:29 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1661855071; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HUH+ZpuDeiFABhrLrRpOqKqhbAcqK/Lcv9H+mHNqG2Y=; b=z1xmTM4ha8NYL4Pj7YkC4XzfLdL8pKnTm/+FfPTCZhm515H6H+TBsj7Mv2HI5Ne6VMOti4 kZk3Do2phz+tu+BK6nS3SK185Y2UT/q8QCHxrZ2bw3A9RFoLyrJfaJ/G6XdNH2j6khsrc4 RE7enFnCpkQapljR+VoLVz4LuLUjWCupYsdbgdQ/oHeXyGmJqIh7+3qcK8ON1UdhAidtdb OxNFFXJkwCTfVNNUCXignPQzAvGWXFlxPywEEvbZiGhtGfUWFWOcDLqm7F9s1dScNrcSIF fYbuV4mXzhYCXM4EXQoudL5WQn+KweR4DSM7ommmqPPHqXXnAE7Gvqxd5CWGFg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1661855071; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HUH+ZpuDeiFABhrLrRpOqKqhbAcqK/Lcv9H+mHNqG2Y=; b=/SkBUZOPBbawnhtG4VKOA1wPBgAOGegOM0sIKXRV1R6jLMVLoi/V317dbYxd1VTMrD21Pq Z5nl7yTZSWfauDDw== From: Sebastian Andrzej Siewior To: Maurizio Lombardi Cc: vbabka@suse.cz, linux-mm@kvack.org, rientjes@google.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH RFC] mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context. Message-ID: References: <20220829154805.1205507-1-mlombard@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20220829154805.1205507-1-mlombard@redhat.com> ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=z1xmTM4h; dkim=pass header.d=linutronix.de header.s=2020e header.b="/SkBUZOP"; spf=pass (imf30.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661855073; a=rsa-sha256; cv=none; b=HhcvfZrTA4C0JvglYg9DDN0bC6wz+WaJ4ZrLERpMwnOO1KwUJW6Xl8ViE+NysQzvdJNlSK FPvq4SL7Rg9p+Akmj+VeWS5xnUR2qc0nqAxbFfZZC33b45StiG7Agpb261IxCkZaaQbE2a lk4Z5uiQqdFtwwcNElkkarCr+9DPg9U= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661855073; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=HUH+ZpuDeiFABhrLrRpOqKqhbAcqK/Lcv9H+mHNqG2Y=; b=Wjr1lAs9Z6xF+6wwMgXWmNcCpKEemPhtjFfjOQm7y+GRzOxLpDBf52NItP3Y/j352w6Vpc 8Wbh991PJh/+aaWFAc8/Ir1B+9OJXJuNRdn24Y+ARRM/MFDFfmTgG3/zMjspn43+a6tvFj mw/ah7wFkzxJ6fUSGmqukwFzSa+gqM8= X-Stat-Signature: dnczzf8jkxgez563egepqd9gaptf7syk X-Rspam-User: Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=z1xmTM4h; dkim=pass header.d=linutronix.de header.s=2020e header.b="/SkBUZOP"; spf=pass (imf30.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2F13E80012 X-HE-Tag: 1661855072-478129 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022-08-29 17:48:05 [+0200], Maurizio Lombardi wrote: > diff --git a/mm/slub.c b/mm/slub.c > index 862dbd9af4f5..d46ee90651d2 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2681,30 +2681,34 @@ struct slub_flush_work { > bool skip; > }; > =20 > +static void flush_cpu_slab(void *d) > +{ > + struct kmem_cache *s =3D d; > + struct kmem_cache_cpu *c =3D this_cpu_ptr(s->cpu_slab); > + > + if (c->slab) > + flush_slab(s, c); > + > + unfreeze_partials(s); > +} =E2=80=A6 > @@ -2721,13 +2725,18 @@ static void flush_all_cpus_locked(struct kmem_cac= he *s) > lockdep_assert_cpus_held(); > mutex_lock(&flush_lock); > =20 > + if (in_task()) { > + on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1); This blocks with disabled preemption until it completes flush_cpu_slab() on all CPUs. That function acquires a local_lock_t which can not be acquired from in-IRQ which is where this function will be invoked due to on_each_cpu_cond(). Couldn't we instead use a workqueue with that WQ_MEM_RECLAIM bit? It may reclaim memory after all ;) Sebastian